1. Field of the Invention
The present invention relates to an image taking apparatus and, more particularly, to a technique of correcting overexposure or underexposure at the time of image taking using flash.
2. Description of the Related Art
In recent years, a digital camera has been proposed which has an increased camera sensitivity such that even a dark-scene image can be taken without emitting flash (Japanese Patent Application Laid-Open No. 2005-20341).
In this digital camera, when the diaphragm stop is minimum (maximum aperture) and when the shutter speed becomes equal to or slower than a camera shake limit speed (e.g., 1/60 sec), the camera sensitivity is increased one step to maintain the shutter speed faster than the camera shake limit speed. When the upper limit value of the camera sensitivity is reached and when the shutter speed becomes equal to or slower than the camera shake limit speed, the shutter speed is maintained at the camera shake limit speed and the flashlight is fired.
A digital camera controlled so as to emit an optimum quantity of flash at the time of actual image taking while reducing the power consumption at the time of pre-emission of flash has also been proposed (Japanese Patent Application Laid-Open No. 2002-207159).
This digital camera has an automatic focusing device for performing automatic focusing based on an evaluation value representing the result of evaluation of contrast of an image, and obtains the accuracy of measurement of the shooting distance with the automatic focusing device (higher the evaluation value, higher the measurement accuracy). When the accuracy of measurement of the shooting distance is high, pre-emission of flash is prohibited and the quantity of flash to be emitted at the time of main emission is determined from the shooting distance, thus preventing wasting of energy by pre-emission.